In a photolithography process, in order to prevent dust (particles) or the like from being attached to a mask or a reticle, a pellicle including a pellicle film extended along one end of a frame of a size appropriate to enclose a mask pattern is used.
The pellicle is originally used to protect a photomask against dust or the like. If a produced pellicle has dust or the like attached thereto, it is meaningless to use the pellicle. Therefore, a pellicle production method that decreases the amount of dust or the like attached to the pellicle is a technology currently strongly desired.
A pellicle, especially a pellicle for EUV, is obtained as follows as described in Japanese Laid-Open Patent Publication No. 2013-004893. A pellicle film is formed on a substrate such as a silicon substrate or the like by CVD, sputtering or any other appropriate film formation method, and then only the substrate is removed by etching or the like while a peripheral frame-like region is left (back-etching). Since etching is generally performed by an existing semiconductor production process, the substrate is processed in a state of being disc-shaped, namely, in a so-called wafer state. Therefore, in order to produce a pellicle film, the substrate for the pellicle film is removed by back-etching and then the pellicle film is trimmed. However, such a pellicle production method has a problem that particles generated at the time of trimming are accumulated on a surface of the film and thus contaminate the pellicle film.